1. Field of the Invention
This invention relates to a sheet for holding transparencies, and more particularly to a transparency-holding sheet which is suitable for application to a projector having an automatic focussing device, so as to project clear images of transparencies such as slide films and microscopic preparations being held by the sheet.
2. Description of the Prior Art
Transparency-holding sheets have been used for classifying, storing, and projecting transparencies such as slide films. A typical transparency-holding sheet of the prior art consists of a transparent or translucent holder sheet, and a plurality of rectangular recesses are formed on the holder sheet so as to hold one transparency in each of such recesses. The bottom wall of each recess protects the emulsion layer of the transparency against scratching or other disturbances from the back of the holder sheet. However, the transparency-holding sheet of the prior art has a shortcoming in that, when the transparency held by such sheet is projected by a projector having an automatic focussing device, light beams reflected by the bottom wall of the recess proceed very close to the reflected light beams from the transparency and tend to cause an erroneous operation of the automatic focussing device. Accordingly, when the picture of the transparency carried by the transparency-holding sheet of the prior art is projected onto a screen by using the projector with the automatic focussing device, the picture projected on the screen is sometimes blurred due to the above-mentioned erroneous operation.